This page made possible by the sponsorship of:
, Edmonton SEO, Tyler Ferrari.

Edmonton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Edmonton clear sky chart from 2005-11-05 to 2017-05-24.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
43%
14905
10%
45692
7%
14877
46%
14877
18%
32892

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
35%
895
6%
2685
4%
895
37%
895
13%
2095
January16th to endNight
32%
903
14%
2823
8%
903
39%
903
17%
2027
February1st to 15thNight
39%
700
8%
2440
7%
697
43%
697
14%
1774
February16th to endNight
48%
632
12%
2019
12%
632
50%
632
18%
1443
March1st to 15thNight
43%
720
13%
2114
10%
720
47%
720
19%
1539
March16th to endNight
41%
768
10%
2089
6%
767
43%
767
16%
1620
April1st to 15thNight
42%
599
12%
1679
7%
599
45%
599
18%
1257
April16th to endNight
41%
540
11%
1620
10%
540
44%
540
18%
1161
May1st to 15thNight
45%
376
7%
1301
6%
376
47%
376
18%
891
May16th to endNight
41%
360
0%
1260
0%
360
41%
360
14%
896
June1st to 15thNight
45%
330
0%
1155
0%
330
45%
330
14%
854
June16th to endNight
53%
330
0%
998
0%
330
53%
330
19%
710
July1st to 15thNight
60%
310
0%
1047
0%
310
60%
310
21%
696
July16th to endNight
57%
348
2%
1141
1%
326
58%
326
20%
735
August1st to 15thNight
63%
336
6%
1275
8%
334
64%
334
21%
797
August16th to endNight
56%
525
11%
1575
10%
525
57%
525
26%
1032
September1st to 15thNight
60%
575
15%
1625
12%
575
61%
575
32%
1017
September16th to endNight
55%
656
19%
1815
13%
656
59%
656
34%
1126
October1st to 15thNight
43%
660
14%
1974
10%
660
47%
660
21%
1382
October16th to endNight
42%
707
14%
2291
11%
707
47%
707
19%
1589
November1st to 15thNight
34%
875
14%
2486
9%
875
39%
875
17%
1883
November16th to endNight
32%
900
10%
2700
5%
900
36%
900
14%
2096
December1st to 15thNight
32%
900
9%
2700
6%
900
35%
900
12%
2123
December16th to endNight
38%
960
11%
2880
6%
960
42%
960
16%
2149

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
11%9%47%6%35%5%6%8%30%
46615
Night
9%9%48%7%35%5%6%7%30%
45843
TransparencyDay
49%8%18%18%5%
46265
Night
50%8%16%18%6%
45697
SeeingDay
15%420%31%20%6%
5769
Night
14%424%35%18%2
14916

By Month

Percentage Cloud Cover NW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
6%11%6%12%10%5%6%45%7%24%
1253
16th to endDay
6%14%6%9%9%25%5%5%7%27%
1410
February1st to 15thDay
8%13%5%10%7%45%46%7%26%
1421
16th to endDay
5%12%8%11%8%46%6%6%7%22%
1453
March1st to 15thDay
8%12%6%10%9%445%7%7%24%
1845
16th to endDay
12%12%6%8%6%45%5%6%9%22%
2131
April1st to 15thDay
12%10%47%6%36%5%5%7%29%
2269
16th to endDay
13%13%36%5%35%6%5%8%28%
2340
May1st to 15thDay
10%8%37%6%46%5%6%8%33%
2649
16th to endDay
18%7%36%6%26%45%7%29%
2694
June1st to 15thDay
16%8%48%7%46%5%6%6%25%
2475
16th to endDay
14%7%25%6%36%6%7%7%31%
2629
July1st to 15thDay
11%6%25%6%35%5%6%9%35%
2510
16th to endDay
11%4145%45%5%7%9%39%
2636
August1st to 15thDay
9%7%25%5%35%6%7%10%34%
2346
16th to endDay
9%5%25%5%445%7%10%38%
2275
September1st to 15thDay
12%7%25%5%345%5%8%39%
2005
16th to endDay
11%4245%3446%8%44%
1815
October1st to 15thDay
12%9%47%6%36%5%45%34%
1656
16th to endDay
11%10%47%5%245%7%8%31%
1569
November1st to 15thDay
9%12%5%8%6%36%5%5%8%28%
1370
16th to endDay
7%12%6%11%6%445%6%6%29%
1260
December1st to 15thDay
7%14%7%11%10%6%6%5%5%6%19%
1260
16th to endDay
6%12%5%10%9%5%7%5%6%8%22%
1344
January1st to 15thNight
7%12%6%10%8%5%6%5%5%6%24%
2685
16th to endNight
7%12%5%9%8%4446%8%30%
2823
February1st to 15thNight
6%10%5%12%8%36%5%5%5%28%
2432
16th to endNight
8%11%5%8%5%36%5%6%8%29%
2019
March1st to 15thNight
8%8%49%6%46%6%6%8%29%
2114
16th to endNight
10%11%6%9%7%36%5%7%8%21%
2088
April1st to 15thNight
10%9%49%7%47%5%6%6%29%
1679
16th to endNight
14%10%27%6%45%46%6%31%
1620
May1st to 15thNight
10%6%48%7%46%46%7%33%
1300
16th to endNight
21%8%25%6%25%5%6%7%28%
1260
June1st to 15thNight
14%8%38%6%5%6%5%8%7%25%
1155
16th to endNight
11%7%35%7%46%6%7%9%30%
998
July1st to 15thNight
11%5%16%6%35%6%8%11%34%
1117
16th to endNight
9%435%447%5%7%10%36%
1225
August1st to 15thNight
9%426%5%37%5%7%9%40%
1282
16th to endNight
9%6%26%6%35%6%5%10%38%
1575
September1st to 15thNight
12%425%5%3345%8%45%
1625
16th to endNight
9%4235%2446%8%49%
1815
October1st to 15thNight
11%9%47%6%3445%6%35%
1974
16th to endNight
10%8%36%6%45%5%7%8%32%
2291
November1st to 15thNight
12%11%5%8%6%35%46%6%28%
2486
16th to endNight
7%13%6%10%8%36%5%5%6%26%
2700
December1st to 15thNight
10%13%7%11%8%445%5%6%22%
2700
16th to endNight
5%11%5%11%8%46%5%6%9%24%
2880

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
58%8%14%13%4
1253
16th to endDay
53%8%13%15%7%1
1410
February1st to 15thDay
55%6%18%13%5%
1421
16th to endDay
57%7%13%16%5%
1453
March1st to 15thDay
56%7%16%15%3
1845
16th to endDay
56%8%13%16%4
2132
April1st to 15thDay
51%6%16%18%6%
2269
16th to endDay
51%7%16%16%7%1
2340
May1st to 15thDay
46%7%14%21%10%
2649
16th to endDay
51%7%14%17%8%
2699
June1st to 15thDay
55%8%16%15%3
2475
16th to endDay
47%10%21%17%3
2629
July1st to 15thDay
42%10%23%21%3
2351
16th to endDay
38%11%28%19%1
2457
August1st to 15thDay
39%12%31%14%1
2328
16th to endDay
37%10%25%21%4
2275
September1st to 15thDay
41%8%20%22%6%
2005
16th to endDay
35%7%19%29%6%1
1815
October1st to 15thDay
49%6%16%21%5%
1656
16th to endDay
46%7%16%25%3
1569
November1st to 15thDay
52%7%16%18%4
1370
16th to endDay
52%9%17%15%5%
1260
December1st to 15thDay
65%7%10%13%2
1260
16th to endDay
58%7%13%14%6%
1344
January1st to 15thNight
58%8%16%12%31
2685
16th to endNight
51%7%15%17%6%1
2823
February1st to 15thNight
54%6%16%15%6%
2443
16th to endNight
49%8%14%18%8%1
2019
March1st to 15thNight
49%8%14%19%6%
2114
16th to endNight
56%7%12%17%5%
2091
April1st to 15thNight
53%7%13%17%7%1
1679
16th to endNight
49%8%11%17%11%1
1620
May1st to 15thNight
47%7%11%18%13%1
1301
16th to endNight
53%6%13%15%8%2
1260
June1st to 15thNight
53%9%14%17%4
1155
16th to endNight
46%10%21%17%3
998
July1st to 15thNight
39%12%20%21%5%
1047
16th to endNight
39%11%23%23%2
1141
August1st to 15thNight
37%12%29%19%1
1275
16th to endNight
39%8%21%24%6%
1575
September1st to 15thNight
36%5%19%28%9%
1625
16th to endNight
31%8%16%30%10%2
1815
October1st to 15thNight
48%6%15%22%7%
1974
16th to endNight
46%9%17%22%4
2291
November1st to 15thNight
54%7%11%19%5%
2486
16th to endNight
57%8%14%13%41
2700
December1st to 15thNight
60%7%13%13%4
2700
16th to endNight
54%7%17%16%4
2880

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
10%5%15%38%26%5%
60
16th to endDay
3121%46%15%10%
64
February1st to 15thDay
7%429%32%20%4
64
16th to endDay
15%316%37%20%7%
112
March1st to 15thDay
13%330%37%12%2
270
16th to endDay
19%219%31%24%2
288
April1st to 15thDay
18%7%21%33%15%2
269
16th to endDay
24%5%20%30%13%5%
270
May1st to 15thDay
11%7%22%32%20%5%
444
16th to endDay
20%5%15%31%18%8%
481
June1st to 15thDay
16%6%22%29%20%5%
420
16th to endDay
14%420%27%24%8%
574
July1st to 15thDay
12%217%31%28%7%
435
16th to endDay
13%318%31%27%5%
445
August1st to 15thDay
14%215%29%25%12%
298
16th to endDay
15%6%19%31%22%4
268
September1st to 15thDay
18%5%24%25%20%4
255
16th to endDay
12%11%28%27%15%5%
255
October1st to 15thDay
26%422%27%11%7%
134
16th to endDay
19%418%32%20%4
96
November1st to 15thDay
24%327%36%8%
83
16th to endDay
13%128%26%18%11%
60
December1st to 15thDay
11%33%30%18%6%
60
16th to endDay
9%115%42%21%9%
64
January1st to 15thNight
13%6%27%35%13%3
900
16th to endNight
13%8%29%32%14%1
903
February1st to 15thNight
12%423%37%19%2
704
16th to endNight
13%320%37%21%3
632
March1st to 15thNight
12%325%40%14%2
720
16th to endNight
15%422%35%19%2
768
April1st to 15thNight
14%6%23%36%19%1
599
16th to endNight
19%424%34%16%1
540
May1st to 15thNight
15%320%40%17%1
377
16th to endNight
23%417%31%21%1
361
June1st to 15thNight
17%6%20%36%16%3
330
16th to endNight
14%316%34%29%1
330
July1st to 15thNight
13%114%43%25%
310
16th to endNight
11%319%37%25%2
348
August1st to 15thNight
10%114%33%33%6%
336
16th to endNight
10%220%39%26%1
525
September1st to 15thNight
13%116%41%24%2
575
16th to endNight
11%422%42%16%2
656
October1st to 15thNight
18%324%35%17%1
660
16th to endNight
16%327%37%14%
707
November1st to 15thNight
18%6%29%32%10%1
875
16th to endNight
12%6%30%33%13%3
900
December1st to 15thNight
16%8%26%29%16%3
900
16th to endNight
10%427%35%18%4
960
Page generated at 2017-05-25 11:27:35. Version ac04

Copyright 2017 A. Danko


Edmonton Clear Sky Chart | Charts Home